1. Field of the Invention
The invention relates to a coolable blade according to the preamble of the first claim.
2. Discussion of Background
DE 32 48 162, for example, discloses such coolable blades. In this publication, a coolable blade is described which has a cooling-fluid passage in its leading-edge region. Ribs for initiating and promoting turbulence extend over the width of the cooling-fluid passage and are arranged at an acute angle, approximately 30.degree., to the inside of the leading-edge wall obliquely against the direction of flow of the cooling fluid in the cooling-fluid passage. The ribs are therefore oriented in such a way that the cooling air is directed to the leading edge of the blade. In this case, the rib height is between 10 to 33% of the height of the cooling-fluid passage. At the same time, the rib height is in each case constant over the width of the cooling-fluid passage and the cooling arrangement can only be used for the nose passage in the region of the leading edge.
In the rear stages of a modern gas turbine, the high outside temperature likewise requires the blade to be cooled, although the blade here is of a very slim form for aerodynamic reasons. This results in an essentially double triangular-shaped coolant passage having acute-angled triangular points in the region of the leading and trailing edge of the blade. The flow resistance is very high in the region of the acute-angled triangular points and therefore virtually no cooling takes place in these regions.